How to Install GCCM: SITE PREPARATION, HYDRATION AND JOINTING

How to Install GCCM: Site Preparation, Hydration and Jointing

Geosynthetic Cementitious Composite Mat, commonly known as GCCM, cement blanket or concrete mat, provides a faster and more practical alternative to conventional concrete for many erosion-control and infrastructure applications.

GCCM is supplied in flexible rolls containing a specialised dry cementitious mixture held between geosynthetic layers. The material is positioned over the prepared surface, secured, joined and hydrated with water. After hydration, it cures to form a durable concrete layer that follows the profile of the underlying surface.

Although GCCM installation generally requires less equipment and formwork than conventional concrete, correct preparation, jointing, anchoring and hydration remain essential. Installation requirements may also vary according to the GCCM grade, site conditions and intended application.

This guide explains the typical GCCM installation process for slopes, drainage channels, canals, culverts and other infrastructure applications.

Where Can GCCM Be Installed?

GCCM may be considered for applications including:

• Slope and embankment protection
• Erosion control
• Drainage and monsoon channels
• Canal and irrigation lining
• Culvert rehabilitation
• Spillways and outfalls
• Mining drainage
• Industrial bund lining
• Plantation drainage systems
• Weed suppression
• Riverbank protection

The selected GCCM grade and installation method should be appropriate for the expected water flow, ground conditions, slope profile and project specifications.

Equipment Required for GCCM Installation

One of the main advantages of concrete mat installation is its relatively simple equipment requirement. Depending on the size and location of the project, installers may require:

• Excavator or lifting equipment for bulk rolls
• Portable dispensing equipment for smaller rolls
• Cutting tools suitable for GCCM
• Ground pegs, anchors or fixings
• Stainless-steel screws or approved mechanical fasteners
• Sealant or jointing compound where specified
• Water hose or spraying equipment
• Measuring tape and marking equipment
• Personal protective equipment
• Compaction equipment for substrate preparation

The exact tools and fixings should follow the manufacturer’s installation guidance and the project engineer’s approved method statement.

Step 1: Inspect and Prepare the Site

Proper site preparation is the foundation of a successful GCCM installation.

Remove vegetation, loose soil, sharp objects, debris and any other material that could create voids or damage the underside of the mat. The substrate should be stable, reasonably smooth and properly compacted.

Large holes, soft areas and sudden changes in level should be repaired before the GCCM is positioned. Where water is present, temporary diversion or dewatering may be required to provide a safe and workable installation surface.

For slope applications, crest and toe anchor trenches may need to be prepared before the material is unrolled. For channel applications, the substrate should be shaped to the required channel profile and cleared of anything that could prevent close contact between the GCCM and the ground.

The amount of preparation required will depend on:

• Soil type and stability
• Existing erosion
• Slope angle
• Water-flow conditions
• Ground profile
• Anchor design
• Project specification

GCCM should generally remain in close contact with the substrate. Unsupported sections, bridging and large voids should be avoided.

Step 2: Plan the GCCM Layout

Before unrolling the material, determine the direction in which the GCCM sheets will be installed.

The layout should minimise unnecessary joints, offcuts and complex overlaps. Installers should also consider the direction of water flow.

For drainage channels and canals, the joint arrangement should be designed to reduce the possibility of water entering beneath the upstream edge. For slopes, the material is commonly positioned from the crest towards the toe, subject to the approved installation design.

The layout plan should identify:

• Roll direction
• Starting and finishing points
• Longitudinal and transverse joints
• Required overlaps
• Anchor trenches
• Fixing positions
• Pipe penetrations and structures
• Areas requiring cutting or shaping

Careful planning can reduce material waste and improve installation efficiency.

Step 3: Unroll and Position the GCCM

Move the GCCM roll into position using suitable lifting or dispensing equipment. Small rolls may be handled using portable equipment, while larger bulk rolls will normally require mechanical lifting.

Unroll the GCCM carefully across the prepared substrate. The material should be positioned with the correct surface facing upwards in accordance with the manufacturer’s instructions.

Avoid dragging the mat over sharp objects or stretching it excessively. Adjust the material so that it follows the surface profile and maintains close contact with the substrate.

GCCM can normally be cut and shaped on-site to accommodate:

• Curved drains
• Irregular slopes
• Culvert entrances
• Pipes and penetrations
• Headwalls
• Corners
• Existing concrete structures

All cut sections should be adequately secured and sealed where required.

Step 4: Overlap and Join Adjacent Sheets

Correct jointing is one of the most important parts of cement blanket installation. Poorly formed joints may allow water to enter beneath the material or cause sections to separate during service.

Adjacent GCCM sheets are normally installed with an overlap. The required overlap width and jointing method must follow the product manufacturer’s instructions and the project design.

Depending on the application, joints may be formed using:

• Mechanical screws or approved fasteners
• Adhesive sealant
• Thermal bonding for compatible liner systems
• Mortared joints
• A combination of sealing and mechanical fastening

Overlaps should be kept clean and free from loose soil or debris before they are secured. In water-flow applications, the upstream sheet should normally overlap the downstream sheet so that water passes over the joint instead of against an exposed edge.

Where GCCM meets existing concrete, steel, pipes or other structures, the termination detail should be properly sealed and mechanically secured.

Step 5: Anchor and Secure the GCCM

The GCCM must be secured so that it remains in position during hydration, curing and operation.

Anchoring requirements depend on the application, slope gradient, substrate and expected hydraulic forces. Common fixing methods include:

• Ground pegs
• Soil anchors
• Anchor trenches
• Stainless-steel fixings
• Concrete screws
• Battens or termination bars
• Approved mechanical fasteners

For slopes, the top edge may be secured inside a crest anchor trench. Additional fixings may be required across the slope and at the toe.

For drainage channels, attention should be given to the channel edges, joints, transitions, inlets and outlets. Areas exposed to concentrated or turbulent flow may require additional anchoring and protection.

Anchor spacing should be determined by the approved design rather than applied as a single standard measurement for every site.

Step 6: Hydrate the GCCM

Once the GCCM has been positioned, joined and secured, it can be hydrated.

Apply water evenly across the exposed surface using a hose, spray nozzle or other suitable equipment. The entire cementitious section must receive sufficient water for proper hydration.

The water should be applied as a spray rather than a high-pressure jet that could disturb the material before it begins to set. Pay particular attention to:

• Overlaps
• Edges
• Cut sections
• Vertical surfaces
• Areas around fixings
• Curves and depressions

Depending on the GCCM specification, fresh, brackish or seawater may be acceptable. However, the permitted water quality and required water volume must be confirmed against the manufacturer’s technical datasheet.

Avoid relying on rainfall alone unless this is expressly permitted by the manufacturer and controlled under the installation method statement.

Some products or environmental conditions may require a second application of water to ensure complete hydration.

Step 7: Allow the Material to Cure

After hydration, protect the installed GCCM from displacement, traffic and physical damage while it sets.

Initial setting and full curing times vary according to the product, temperature, weather conditions and level of hydration. The installation area should not be put into service until the required curing period has been completed.

During curing:

• Prevent vehicles or equipment from travelling over the material
• Avoid disturbing joints and fixings
• Inspect for dry or insufficiently hydrated areas
• Protect the installation from unexpected water flow where necessary
• Follow the manufacturer’s minimum curing requirements

Where the GCCM is installed in an active drain or channel, water should only be reintroduced according to the approved method statement.

Step 8: Conduct a Final Inspection

The completed installation should be inspected before handover.

The inspection should confirm that:

• The GCCM follows the substrate without major voids
• All joints have the required overlap
• Joints and terminations are properly secured
• Fixings have been installed at the specified spacing
• Edges are anchored or terminated correctly
• The surface has been uniformly hydrated
• There are no damaged or displaced sections
• Penetrations and transitions are properly sealed
• The material has completed the required curing period

Any damaged, dry or incorrectly joined areas should be repaired according to the manufacturer’s approved repair method.

Standard GCCM and GCCM LWP

Not every GCCM product has the same layer construction.

Standard GCCM typically contains a specialised cementitious mixture positioned between geotextile layers. It is commonly considered for erosion control, slope protection, drain lining and similar civil-engineering applications.

GCCM LWP includes an additional HDPE protective layer. This construction may be suitable for applications requiring enhanced water containment or barrier performance.

The appropriate product should be selected based on the project’s hydraulic, mechanical and containment requirements. Contractors should not assume that all GCCM grades provide identical performance.

Common GCCM Installation Mistakes

Several installation problems can be prevented through proper planning and supervision.

Inadequate substrate preparation

Loose soil, vegetation and large voids can prevent the GCCM from maintaining close contact with the ground.

Incorrect overlap direction

Joints facing against the direction of water flow may increase the risk of water entering beneath the mat.

Insufficient anchoring

Inadequate fixings may allow the material to move during hydration or under hydraulic loading.

Uneven hydration

Dry sections may not cure correctly and can affect the performance of the completed installation.

Unsealed terminations

Edges around pipes, structures and existing concrete must be properly detailed to prevent water ingress.

Using one method for every application

A slope, drainage channel and industrial containment area may each require different GCCM grades, jointing systems and anchor designs.

Is GCCM Easier to Install Than Conventional Concrete?

GCCM can significantly simplify construction in locations where conventional concrete would require extensive formwork, batching, pumping or specialist access.

Because the material is supplied in rolls and hydrated after positioning, it can be particularly useful for remote sites, confined spaces and irregular terrain. However, its performance still depends on proper product selection and installation.

Site conditions, water velocity, loading, chemical exposure and engineering requirements should be reviewed before deciding whether GCCM is suitable for a particular project.

GCCM Supply and Technical Support in Malaysia

Delta Corp supplies Geosynthetic Cementitious Composite Mat for infrastructure, drainage, erosion-control, mining, industrial and plantation applications in Malaysia.

Our team can assist with:

• Selection between standard GCCM and GCCM LWP
• Product thickness and grade selection
• Estimated material quantities
• Technical datasheets
• Installation guidance
• Project-specific quotations

For a product recommendation, send us your project drawings, application details, site location and estimated installation area.

[View Delta Corp’s GCCM product range]

[Contact Delta Corp for a GCCM quotation]

Frequently Asked Questions

What is required for GCCM installation?

A typical GCCM installation involves preparing the substrate, planning the roll layout, positioning the material, overlapping and joining adjacent sheets, installing anchors, hydrating the GCCM and allowing it to cure.

Does GCCM require concrete mixing?

No on-site concrete batching is normally required. The dry cementitious mixture is contained within the GCCM and is activated by applying water after installation.

How much should GCCM sheets overlap?

The required overlap depends on the product, application and jointing method. Installers should follow the manufacturer’s technical guidance and the approved project method statement.

Can GCCM be installed on a slope?

Yes. GCCM is commonly used for slope and embankment protection. The slope must be properly prepared, and suitable crest, intermediate and toe anchoring may be required.

Can GCCM be cut on-site?

GCCM can generally be cut and shaped before hydration using suitable tools. Cut edges, penetrations and terminations must be secured and sealed according to the installation specification.

Can seawater be used to hydrate GCCM?

Certain GCCM products may permit hydration using fresh, brackish or seawater. Always confirm the acceptable water source in the technical datasheet for the selected product.

Is GCCM the same as a cement blanket or concrete mat?

“Cement blanket” and “concrete mat” are commonly used commercial descriptions for roll-based cementitious materials. GCCM—Geosynthetic Cementitious Composite Mat—is the recognised technical category. Product composition and performance can differ between manufacturers.